I have 6 eggs on day 27, 3 of them had internally pipped last night at 9pm. I waited 20 hours and there was no external pip but the babies were peeping and rocking those eggs. So at 5pm today I made a tiny hole in each egg close to the babies beaks so they could get some air. I can see one of the babies tapping on the egg but it's not breaking. How long can I leave them like this before I need to intervene more? Could the egg be so hard that they can't break it? I don't want to help more than nessasary, but I don't plan on allowing them to die if I can help them. Thank you